1. Field of the Invention
This invention relates to methods and compositions for treating kidney stones. More particularly, this invention relates to compositions containing water-soluble vinylbenzenesulfonic acid polymers and their use in treating kidney stones.
2. Description of the Prior Art
In the United States alone, there are each year about 250,000 newly diagnosed patients with kidney stones. Analysis of these stones shows that 70% of all kidney calculi contain calcium. Successful treatment of calcium containing kidney calculi occurs with the reduction of urinary calcium excretion. Urinary calcium excretion can be lowered by the oral administration of a calcium sequestrant which binds calcium in the gastrointestinal tract. In essence, by increasing the fecal calcium load, calcium sequestrants decrease the calcium load on the kidney.
The binding and removal of calcium by highly cross-linked carboxylic resins is known and has been used in the removal of calcium from water and blood. In 1968, Burghele et al. (Urologe, 6:234 (1968)) introduced the use of highly cross-linked insoluble resins as a means of kidney stone prophylaxis. See also, Pak et al. (New England J. Med., 290:4, 1974), Successful Treatment of Recurrent Nephrolithiasis (Calcium Stones) with Cellulose Phosphate, and British Pat. No. 1,498,101, Drugs for Use in the Prevention and Treatment of Lithiasis. Water-soluble and swellable carboxylic acid polymers which are calcium sequestrants are disclosed in U.S. Pat. No. 4,143,130.
The water-soluble vinylbenzenesulfonic acid polymers used in this invention are known products of commerce sold by the National Starch and Chemical Corporation and are disclosed as useful for treating ulcers and inhibiting the action of pepsin in U.S. Pat. Nos. 3,961,045 and 3,893,890.